Huge 'bubbletrons' post-Big Bang may have shaped early cosmos

How did these giant bubbles come into existence? 

Four fundamental forces of nature govern everything in the universe: electromagnetism, strong nuclear, weak nuclear, and gravity. 

These forces even shape our daily activities, whether we notice it or not — from playing basketball to placing a magnet on the refrigerator. 

Physicists have long hypothesized that in an extremely high-energy environment, these forces would have functioned as a single great force of the universe (unified force).

According to the authors, the merger of these four forces could have occurred very shortly, or even seconds after the Big Bang, when the universe was filled with a tremendous amount of energy. 

However, as the early universe cooled and expanded, the united forces may have gradually started to separate in a series of phase transitions. 

The enormous bubbles might have formed in between these transitions. 

According to reports, the forces within these bubbles would have been entirely segregated while maintaining cohesion outside them. Over time, these bubbles expanded and collided at high velocities, resulting in the profound transformation of the early universe.

The new study also indicates that the collision and expansion of the bubbletrons would have produced gravitational waves, which are still present billions of years later — like a background hum in the universe. 

The study also suggests that our current understanding of the early universe is merely the surface of a vast iceberg, with numerous concealed mechanisms awaiting discovery.

Scientists expect that the upcoming advanced detectors — like LISA and the Einstein Telescope — would allow them to collect direct proof of bubbletrons. Fresh insights from these technologies may expand our understanding of the hypothetical dark matter and the early years of the universe.

The study has been uploaded to the pre-print server arXiv.

Study Abstract:

In cosmological first-order phase transitions (PT) with relativistic bubble walls, high-energy shells of particles generically form on the inner and outer sides of the walls. Shells from different bubbles can then collide with energies much larger than the PT or inflation scales, and with sizeable rates, realising a `bubbletron'. As an application, we calculate the maximal dark matter mass MDM that can be produced from shell collisions in a U(1) gauge PT, for scales of the PT vφ from MeV to 1016GeV. We find for example MDM∼106/1011/1015 GeV for vφ∼10−2/103/108 GeV. The gravity wave signal sourced at the PT then links Pulsar Timing Arrays with the PeV scale, LISA with the ZeV one, and the Einstein Telescope with grand unification.